This book is based on a study of five infants in vulnerable circumstances, in which the infants were all observed weekly, in their own homes, from birth to two years. The study traces in close detail the developing relationships between the infants and their parents, paying particular attention to the qualities of emotionality in these relationships. This provides a context for understanding and assessing the infants' development and the emergent qualities of their personalities. As the infants are in vulnerable circumstances, there is a particular emphasis on evaluating how the vicissitudes of development in the context of these family relationships contribute to either risk or resilience. Taking an exploratory approach, focusing on discovery more than validation, the book assesses the contribution the approach can make to the development of new theoretical knowledge, and therefore to deepening understanding of infancy. The relationship between the infant observation method and psychoanalytic and child developmental theories of infancy provides the intellectual framework for the study.